Project Summary/ Abstract The World Health Organization ranks migraine as the 3rd most prevalent disease worldwide and 8th most disabling (4th most in women) making it the most common neurological disorder. One of the primary reasons for the disabling nature of migraine is the poor efficacy of currently available therapeutics. Less than 50% of patients achieve complete relief with acute agents such as triptans and only half of patients achieve 50% relief with preventative agents. Our long-term goal is to identify new targets and develop novel therapeutics against these targets to treat this common and debilitating disorder. One of the most consistent triggers for migraine is administration of a nitric oxide (NO) donor. Approximately 75% of human migraine patients will develop an attack within 6 hours of NO donor administration. Despite this observation, migraine therapeutics based on NO or its downstream mechanisms have not yet been developed. The objective of this proposal is to test whether several compounds under development by CerSci Therapeutics that scavenge or catalyze the decomposition of peroxynitrite (PN), the reaction product of NO and superoxide, have efficacy in preclinical models of migraine. Studies over the last decade have shown that PN is an important activator/sensitizer of sensory neurons in preclinical pain models of neuropathic, inflammatory, and cancer pain and agents that eliminate PN have demonstrated efficacy in preclinical pain models. However, studies have not examined whether targeting PN is efficacious for migraine despite the observation that the only pain state triggered by administration of a PN-producing stimulus is migraine (NO donors do not directly cause other types of pain). Thus, we propose to test the hypothesis that CST compounds will decrease NO donor- induced migraine-related behavior in preclinical models via decreased PN. The rationale for the proposed study is that it 1) will demonstrate that scavenging or catalyzing the decomposition of PN is a novel therapeutic avenue to treat migraine; and 2) will provide the preclinical rationale for the development of CerSci compounds that are PN scavengers/decomposition catalysts to treat migraine. We will test the hypothesis with 2 Aims using preclinical rodent models: Aim 1 will test the efficacy of CerSci compounds (CST-10,133, CST-10,243, and CST-10,468) against NO donor-induced migraine behavior in rats primed by dura mater administration of the cytokine interleukin-6 (IL-6). Aim 2 will test the efficacy of CerSci compounds (CST-10,133, CST-10,243, and CST-10,468) against NO donor-induced migraine behavior in mice primed by repetitive stress. This innovative study will for the first time investigate the efficacy of non- metal based, orally-available PN scavengers/decomposition catalysts in preclinical model that mimic conditions relevant to migraine. The significance of the proposal is that it both advances our understanding of migraine mechanisms and has the potential to lead to novel therapeutics.